Cryptology ePrint Archive: Report 2004/336

Oblivious Transfer Is Symmetric

Stefan Wolf and Jürg Wullschleger

Abstract: We show that oblivious transfer of bits from $A$ to $B$ can be
obtained from a single instance of the same primitive from $B$ to $A$.
Our reduction is perfect and shows that oblivious transfer is in fact
a symmetric functionality. This solves an open problem posed by
Crépeau and Sántha in 1991.